The present invention relates to a cutting knife for a cutting tool for cutting through adhesive beads on glass panes of vehicles, having a cross section that is bent into a U-shape and comprises a first limb, configured as the attachment part, with a receiving opening for attachment to an oscillating drive, and a second limb that is configured as the cutting part and is joined via an intermediate part to the attachment part of the cutting knife, the intermediate part and the cutting part being shaped such that a distance exists in the radial direction between the center point of the receiving opening and at least one cutting edge.
Cutting knives of this kind bent into a U-shape are known, for example, from DE 33 24 676 C1 or from EP 0 141 035 B1: the former discloses a cutting part, curved in a sickle shape, that is curved convexly with respect to the clamping point; while the latter discloses a cutting part, curved in a sickle shape, that is curved concavely with respect to the clamping point.
Also known from EP 0 369 390 A2 is a cutting knife having a straight cutting part.
Cutting knives of this kind are used to detach glass panes that are adhesively bonded onto motor vehicles using an adhesive bead. This may involve, for example, a windshield that is adhesively bonded onto the A-pillar of a motor vehicle using an adhesive bead around the entire periphery. The adhesive bead is applied continuously between the body flange and the side of the glass pane facing toward the vehicle interior, and is usually made of a special polyurethane. Windshields adhesively bonded in this fashion additionally impart improved mechanical passenger compartment stability to the vehicle. It is understood that for this reason, the adhesive bead is made of a particularly tough and strong material that presents a great deal of resistance to removal of the windshield. Depending on the adhesive material used, the adhesive bead can also exhibit a certain porosity and, in particular, can possess sufficient toughness that normal cutting is possible only with difficulty even with the use of the oscillating drive, which as a rule oscillates at high frequency (on the order of approximately 5,000 to 25,000 oscillations per minute) and with a small pivot angle (between approximately 0.5 and 5xc2x0).
It is an object of the invention to improve a cutting knife of the kind cited initially in such a way that even adhesive beads that are made of a particularly tough and resilient material can be cut through with relatively little energy expenditure.
This object and other objects are achieved, in the case of a cutting knife of the kind cited initially, in that the cutting part has, in a middle region between its outer free end and its angled transition to the intermediate part, a width that is greater than the width at the transition to the intermediate part.
The object of the invention is completely achieved in this fashion.
Specifically, it has been found that because the cutting part initially widens outward from the transition to the intermediate part, a kind of chopping effect occurs which facilitates cutting through the particularly tough materials that are most recently being used.
According to another embodiment of the invention, the cutting part has a first edge, facing toward the receiving opening and convexly curved with respect thereto, and a second edge, facing away from the receiving opening and concavely curved with respect thereto, at least one of the edges being configured as a cutting edge.
According to a further feature of the invention, the cutting part has a first edge, facing toward the receiving opening and straight or concavely curved with respect thereto, and a second edge, facing away from the receiving opening and concavely curved with respect thereto, at least one of the edges being configured as a cutting edge.
According to a further embodiment of the invention, the cutting part has a first edge, facing toward the receiving opening and convexly curved with respect thereto, and a second edge, facing away from the receiving opening, that is straight or is convexly curved with respect to the receiving opening, at least one of the edges being configured as a cutting edge.
According to a further embodiment of the invention, the cutting part is shaped so that the radial distance to the center point of the receiving opening increases from the transition out toward the outer end.
This feature helps to utilize the oscillation stroke itself for the cutting effect, since with each oscillation stroke the cutting part cuts further into the material that is to be cut through.
According to a further feature of the invention, the cutting part has two cutting edges that meet each other to form a tip at its outer end.
This facilitates insertion of the cutting knife through the adhesive bead at the beginning of the removal operation.
According to a further embodiment of the invention, the cutting part has a cutting edge on its side facing away from the receiving opening, and has on its side facing toward the receiving opening an edge that is configured as a blunt back.
The result of this feature is that the cutting part as a whole has a greater mass, thus increasing the kinetic energy of an oscillation stroke; this makes it easier to cut through particularly tough or porous materials.
It is understood that the features of the invention mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the context of the present invention.